1. Field of the Invention
The present invention relates to a linear anatomic surgical stapling instrument and a surgical staple magazine used therein. More particularly, the invention relates to a gastrointestinal anatomic stapling instrument, which is also known as a gastrointestinal anastomosis instrument or device, for suturing body organs and tissue and to such an instrument that includes a system for preventing its accidental reuse after a staple cartridge has initially been spent.
2. Description of the Prior Art
Historically, suturing of a surgical or other wound in organs and tissue has been done by hand. Conventional hand suturing techniques require a high degree of surgical skill. However, expertise in such techniques can vary widely from surgeon to surgeon, thereby resulting in widely varying quality in performance of the concluding steps of an operative procedure. In addition, even very skillful surgeons require a considerable amount of time to suture even relatively small wounds. Therefore, it is possible that an undesirable amount of blood may be lost during the suturing operation.
Accordingly, there has been an increasing tendency in recent years to use surgical staples to suture body organs and tissue after a medical procedure. Surgical staples have been particularly effective in suturing body organs and tissue such as the lung, as well as the esophagus, the stomach, the duodenum, and other body organs in the intestinal tract.
The advent of surgical stapling has provided several marked advantages over known hand suturing techniques. First, since one or more rows of surgical staples are inserted into tissue using a specially adapted instrument that is relatively simple to operate, near uniformity of the closure from one surgeon to the next results. In addition, all staples in the closure are usually inserted simultaneously or in rapid sequence across the entire wound. Therefore, the closure is made very quickly to minimize loss of blood.
The specially adapted instruments for inserting surgical staples are mechanically operated and may be known as anastomosis devices, such as the gastrointestinal anastomosis devices of the type to which this invention relates. In such devices, the staples are loaded in one or more elongated rows into a magazine or cartridge. The magazine is then mounted in the device, which includes a mechanism for pushing, or driving, the staples from the magazine through two or more sections of tissue toward a deforming anvil. At the conclusion of the driving operation, the legs of each staple are clamped or bent, by engagement with the anvil, to a closed configuration to complete the suture and join the tissue sections together.
Known gastrointestinal anastomosis stapling instruments usually include a pair of elongated jaws that are maneuvered to position the tissue to be sutured therebetween. The jaws are then clamped tightly together. One of the jaws supports the staple magazine with at least two laterally spaced rows of staples and cooperating staple drivers, and the other jaw supports an anvil with similar complementary rows of staple-forming pockets, each pair of which is aligned with one staple in the cartridge. A reciprocal slide is mounted with one jaw and when advanced therealong longitudinally actuates staple-driving cam surfaces to sequentially depress the staple drivers and drive the staples through the body tissue toward the anvil. Additionally, a knife blade may be advanced with the cam surfaces to slice the tissue between the two rows of deformed staples immediately following the staple deformation so that the adjacent sutured tissue sections can be separated.
Known surgical stapling instruments of the type described above can be made of reusable materials. However, most stapling instruments employed today are made of disposable materials so that they can be discarded after use on a single patient. The cost of manufacture is thereby lowered and problems associated with handling, repairing, reconditioning, and sterilizing of previously used instruments are eliminated. Specifically, the risk of spreading infection from patient to patient due to improperly sterilized instruments is thus reduced and the surgeon can be confident that each fresh instrument he or she picks up is sharp and in good working order.
While stapling instruments are, therefore, generally made to be disposed of after use for a given patient, it is also known to use one stapling instrument more than one time during an operation on one patient. Thus such instruments are usually designed to be reloaded by replacing a spent staple magazine with a full one.
As may thus be expected, linear stapling instruments provide many benefits, such as those described above. However, they also have certain drawbacks. For one, they have difficulty maintaining a constant tissue gap between the jaws after the jaws are clamped together, and a high constant clamping pressure on tissue between the jaws. More particularly, forces created when the staples are driven through the tissue into the anvil tend to urge the jaws apart and, if not controlled, produce unevenly deformed staples and an unsatisfactory suture.
U.S. Pat. Nos. 4,633,861 (Chow, et al.) and 4,633,874 (Chow, et al.) relate to stapling instrument designs that attempt to counteract such forces by providing a cam mechanism for urging the jaws apart at an opposite end from where the tissue is clamped. The cam mechanism is located in the handle of one of the jaws and is actuated by the sliding motion of a staple-driving pusher bar or slide. Alternative stapling instrument designs are described in U.S. Pat. Nos. 4,429,695 (Green, et al.) and 4,520,817 (Green) and include sliding shoes that project into complementary slots in the upper and the lower jaws to secure the jaws together in opposition to forces otherwise tending to urge the jaws apart. However, these mechanisms for counteracting the forces tending to separate the jaws when the stapling instrument is actuated are complex. Moreover, they require relatively large effort to activate at the beginning of the staple-driving operation. Such effort may be physically difficult for some surgeons to generate and may cause the instrument to jerk abruptly upon such actuation while engaged on the body tissue.
Another drawback of many known linear stapling instruments is that they lack adequate mechanisms to prevent exposure to the knife blade when the jaws are open and to prevent a surgeon from mistakenly attempting to use the instrument when it is loaded with a spent staple magazine. For example, if a surgeon performs a procedure with a stapling instrument having a spent staple magazine, no suture will in fact be formed despite the surgeon's expectations. Therefore, when he removes the instrument from the tissue, the wound will not be closed and may bleed.
Some attempts have been made to address these latter difficulties. For example, U.S. Pat. No. 4,892,244 (Fox) relates to surgical staple magazines having various safety features designed to prevent the reloading or refiring of the magazines once spent. However, the designs disclosed in that patent do not prevent the jaws of the stapling instrument from being closed on tissue to be sutured while it contains a spent staple magazine that has not been replaced with a loaded one. Therefore, the surgeon may reclamp the instrument and actuate it, expecting a proper suture to have been formed when it has not.
Accordingly, further advances and improvements in linear surgical stapling instruments are needed.